Turbo-propeller



W. PERROTT Nov. 4, 1952 TURBO-PROPELLER 2 SHEETS-SHEET 1 Filed June 3, 1948 INVENTOR.

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TURBO-PROPELLER Filed June 3. 1948 2 SHEETS-SHEET 2 7 a s 6' '70 /s IN VEN TOR.

%M 21125, (u/Q W Patented Nov. 4, 1952 UNITED STATES PATENT OFFECE TURBO-PROPELLER ware Application June 3, 1948, Serial No. 30,829

4 Claims. 1

The specification which follows relates to an improvement in propellers for Ships and airplanes and impellers for liquid pumps, fans and the like.

The conventional and generally adopted theory of propeller fans and the like is based upon an Archimedian screw. This presupposes a spiral thread of a helix or a plurality of such which occupy a cylindrical space around the axis of a rotating drive shaft. Devices of this type are characterized by a flow of fluid which while being received in an axial direction is discharged and deflected away from that direction. There results a zone of low pressure in the axial region behind the propeller and an undesirable disturbance is caused by the discharge of the fluid flow of the stream in a divergent path.

The present invention differs basically in that the novel turbo-propeller while receiving the stream in an axial direction diverts it to a minimum extent and restricts the line of discharge of propulsion to parallelism with the axis.

One of the objects of the invention is to utilize the principle of trochoidal action, for with the curvilinear design on the suction side, propeller efficiency is improved, turbulence reduced, thereby totally eliminating back pressure, making possible air or fluid motion across the moving blade equal to the rotating blade velocities. In trochoidal action we approach perfection in propeller efiiciency, for we arrive at a point where a condition has been created wher the outflow is equal to the entrance flow, which condition can only be obtained by a curve which is generated by a point on a circle which rolls on a straight line, and admits of rotation on a longitudinal axis.

The efiect of combining the hemispherical rotor with the generally radial blades, is to effect a negative pressure (vacuum) at or near the axis, for every thread of the turbo-propeller in its spherical spiral out has a motion clearly different from that produced by other propulsing and revolving bodies, for (a) the cone eifectively has a spiral (helix) outsetting from the vortex and developing interminally (endless core) in coaxial diverging spirals and (b) the turbo-cylinder, however, propelling and advancing at uniform velocity will effect a motion of subservience to carry off current of helicoidal spirals.

It thus follows that an object attained by this invention is to produce a longitudinal vortex flow which will lower the pressure at the axis and thus lower cavitation.

A still further object of the invention, in giving the blades the concave and convex shape on the thrust and suction sides respectively, so that the thickness may be smaller than the other types of propellers, is to reduce its resistance at the point or entrance of penetration, thus increasing power of the thrust of the central rectilinear vortex, created and maintained by effect of induction.

By way of example and without limitation, the invention has been illustrated in the accompanying drawings in which:

Fig. 1 is a rear elevation of the improved propeller;

Fig. 2 is a side elevation of the same.

Fig. 3 is a longitudinal section on line 33 of Fig. 1;

Fig. 4 is a diagrammatic view of the fluid current through the propeller, and

Fig. 5 is a view in cross-section, of the blade taken on line 55 of Fig. 3.

The above objects of the invention are obtained by an improved design for both the rotary shell and the radial blades.

As illustrated, the propeller is shown to comrise a central hub 1 which has a stream-line tip 8. The hub is, of course, rigidly attached to the propelling or drive shaft. A part-spherical rotor 9 is provided. This is specifically a zone of a sphere comprised between parallel planes one of which is substantially the maximum diameter of the sphere.

This zone or rotor is held in a position axially of and spaced from the driving shaft. The support consists of the bases Iii of the blades H. The blades are therefore rigidly supported by the zone 9 which forms a circumferential reinforcement between the intermediate parts of the blades.

As shown in Figs. 2 and 3 the leading edge 12 of each blade is curved to the rear or in the direction of fluid flow and may be considered as travelling in a path such as would be generated by the rotation of a circle around its diameter or of a parabola around its axis.

Each blade is inclined from the front edge to the rear edge to provide the desired variable pitch with respect to the axis of rotation. Furthermore, as shown in Fig. 5 the blades are made concave on their thrust or rear surfaces. The effect of this is to enhance the longitudinal factor of propulsion.

Each blade has a tip l3. These tips are flatter, more perpendicular to the axis of rotation and angularly disposed with respect to the blades in general. The tips provide for additional thrust against the air or fluid. This thrust admits of rotation on a longitudinal axis.

In Fig. 4 there is shown by dotted lines the effects produced by the particular configuration or zone member and the individual blades. Thus those streamlines M which are met by the advancing edges of the propeller parts will be slightly diverted. A part of the flow passes between the hub I and the zone member 9. Due to the convexityof the latter the flow is returned to an axial direction as shown.

That portion of the flow which is outside of the zone member 9 will be met by the concave rear side of the blades ll. Thus the outward direction of the flow is correctedrand it is returned to parallelism with the axis.

Due to the maintenanceof parallelism ,of the flow past the members 9 and II, the thrust of the blade tips I3 is not disturbed by the flow from the remaining parts of the propeller. Thus the thrust from the blade tips will be substantially axial. will be apparent. that maximum efficiency is realizedby the conjoint useof the several specific elemental details. Comparison of the present design with comparable known propellers is indicated in the following table:

Given a rotation of 77.5 revolutions per minute, a propeller of one meter diameter advancing one meter per second has an efficiency of 68.6 per cent, while for a normal screw propeller the maximum is about 62per cent.

Propellers constructed in accordance with the improved design give added velocity to the fluid stream thus producing greater propulsion. At the same time there is less cavitation due to the longitudinal direction of the discharged stream. The specific construction of the bladeswith thin design and reduced mass and with concave cross section is a decided factor in the improved results obtained.

While the preferred form of the invention has been described-and illustrated for thepurposeof example, it will be readily apparent that many changes may be made in sizes, proportions and materials without, departing from th scope of the invention as defined in the following claims.

What I claim is:

1. A propeller comprisinga hub, a plurality of rearwardly inclined blades attached to thehub, a rotor in the form of a zone of a sphere with opposite openings of different sizes mounted on the blades concentric to thehuband S aced In carrying out the above arrangement it therefrom with its smaller opening in front, said rotor being substantially as wide as the blades at the point of mounting, and the major portion of the leading edges of the blades lying in a spherical path of revolution.

2. A propeller comprising a hub, a plurality of rearwardly inclined blades attached to the hub, a rotor in the form of a zone of a sphere with opposite openings of different sizes mounted on the blades concentric to the hub and spaced therefrom with its smaller opening in front, said rotor being substantially as Wide as the blades at the point of mounting, and the major portion of theleading-edges of the blades lying in a spherical path of revolution, and relatively flat tips on the blades extending radially in planes substantially at. aright angle to the axis of the hub.

3. A propeller comprising a hub, a plurality of rearwardly inclined blades attached to the hub, a rotor in the form 01 a zone of a sphere with opposite openings of different sizes, mounted intermediatelyon theblades concentric to the hub and spaced therefrom with its smaller opening in front, said rotor being substantially as wide as the blades at the point of mounting, and the blades in cross-section being concave on their rear surfaces.

4. A propeller comprising a hub, a plurality of rearwardly inclined blades attached to the hub, a rotor-in the form of azone of a sphere with opposite openings of different sizes, mounted intermediately on theblades concentric to the hub and having its smaller opening in front, said rotorhaving an inner surface that is concave from front to back diverting the fluid stream into a directionparallel to thehub axis.

WILLIAM PERRO'I'T.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,082,750 Jacomy Dec. 30, 1913 1,414,418 Joray May 2, 1922 1,612,028 Kincaid Dec. 28, 1926 1,826,026 Rudeberg Oct. 6, 1931 1,851,513 Holmstrom Mar. 29, 1932 1,895,252 Kontos Jan. 24, 1933 1,896,222 Chilton Feb. 7, 1933 2,001,896 Ward May 21, 1935 2,047,847 Ambjornson July 14, 1936 2,080,224 Lily May 11, 1937 2,508,160 Hansen May 16, 1950 FOREIGN PATENTS Number Country Date 4,718. Great Britain 1909 OTHER REFERENCES Flight, issue of May 20, 1948, pp. 552-554. (Intake Report) 

